Fluid conveying apparatus



Oct. 1o, 1967 ATTORNEY United States Patent O 4 claims. (ci. 11o-72) This is a division of my application Ser. No. 24,791, filed Apr. 26, 1960 and now abandoned.

The present invention relates to fluid conveying apparatus in general, and more particularly to improvements in an apparatus for conveying a fluid stream at a constant rate against the action of one or more variable influences or obstructions which tend to alter the rate of fluid flow. Among many other ladvantageous uses, the apparatus of my invention may be resorted tol for supplying a constant stream of combustion air to a burner for liquid, gaseous or comminuted solid fuel.

It is an important object of my invention to provide a fluid conveying apparatus whose operation is fully automatic, which is of very simple and compact construction, and which can produce a fluid stream that will flow at a constant ra-te even when the influences or factors, such as the draft in the flue of a fuel burning device, which tend to affect the rate of flow fluctuate within a wide range.

Another object of the invention is to provide an apparat-us whose `operation is not affected by changes in temperature land/or pressure of the surrounding atmosphere.

A further object of the instant invention is to provide an apparatus which can be readily combined with existing fuel burners without necessitating any, or by necessitating minor, alterations in the design of such devices.

Briefly stated, one feature of my invention resides in the provision of a fluid conveying apparatus which comprises a conduit having an linlet portion, an outlet portion and an intermediate section located between such inlet and outlet portions and provided with one or more gaps and/or apertures Ior perforations through which the fluid can be withdrawn from the conduit, an obstruction -connected with one of the -two portions of the conduit and arranged to offer a variable resistance to the flow of fluid therethrough, fluid supplying means forV directing a stream of fluid int-o the inlet portion, and regulating means responsive to changes in the resistanceV offered by the obstruction for withdrawing or for effecting withdrawal throughV the intermediate sectionof the conduit of such quantities of fluid that the rate of fluid `flow through the outlet portion remains constant.

In accordance with one presently preferred embodiment of my invention, the fluid supplying means may comprise a tangential blower which is connected with the inlet portion -of the conduit'and the obstruction may comprise a 'burner connected with the outlet portion and having a flue wherein the draft varies in dependency on atmospheric conditions. The conduit may comprise two diffusers the first of which .is provided with the inlet portion and the second of which is provided. with the outlet portion. The two diffusers comprise additional portions which are adjacent to but spaced from each other and together constitute the intermediate section of the conduit. These diffusers define between themselves a gap wherein the fluid stream flowing from the first diffuser toward the second diffuser remains unconned. The regulating means may -comprise a compartment which is outwardly adjacent -to the first diffuser and communicates with the flue as well as with the interior of the 3,345,961 Patented Oct. 10, 1967 first diffuser so that the rate at which fluid can be withdrawn from the first diffuser into the compartment depends on the draft in the flue.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved apparatus itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of a specific embodiment with reference to the accompanying drawings, in which:

FIG. 1 is a somewhat diagrammatic partly elevational and partly vertical sectional view of an apparatus which embodies one form of the present invention; and

FIG. 2 is a diagram illustrating the relationship -between the amounts of fluid drawn by a flue and uid supplied by a tangenti-al blower shown in FIG. l.

Referring first to FIG. 1, the numeral 1 denotes the housing of a burner which contains .a partiti-0n or baille 1a provided with an opening 2. The burner and its exhaust pipe or flue 3 symbolically represent an obstruction or impediment to the flow of a fluid stream. The flue 3 is connected with a chamber 1b which is located downstream of the partit-ion 1a.

The apparatus further comprises a composite conduit lincluding a first part 10 and a second part 5, each lof these parts being shown in the form of a diffuser. The inlet portion of the conduit is constituted by the left-hand end portion 9 of the diffuser 10 and the outlet portion of the conduit is constituted by the right-hand end portion 4 of the diffuser 5. This outlet portion 4 is connected with the housing 1 and discharges into a second chamber 1c which is located upstream of the partition 1a. The diffusers 5 land 10 taper in a direction away from the housing 1.

T-he means for supplying an air stream at constant ,pressure comprises a tangential blower B which is connected with the .inlet por-tion 9 of the left-hand diffuser 10. Since the draft or suction in the flue 3 varies at a non-predictable rate, the apparatus of my invention is further provided with a regulating unit for controlling the escape of air from the conduit at a rate which is a function of the suction prevailing in the flue 3. This regulating unit withdraws air from an intermediate section 0f the conduit and such intermediate section includes the larger-diameter end portion 10a of the first diffuser 410 and the smaller-diameter end porti-on 13 of the second diffuser 5. These end portions 10a, 13 are adjacent to but spaced from each other and together define an annular `gap G wherein the air stream flowing from the diffuser 10 toward the diffuser 5 remains unconned.

` The purpose of my apparatus is to insure that the rate of air flow through the outlet portion 4 of the second diffuser 5 remains constant, i.e., that the housing 1 of the Iburner invariably receives a constant amount of combustion air. This is achieved by supplying combustion air solely from the blower B and/0r in part from the blower B and in part via gap G.

It was found that a tangential blower is particularly suited for use in the apparatus of my present invention. As shown in FIG. 1, the blower B comprises a rotor 6 cooperating with guide walls 7, 8 -to produce a potential Vortex whose core is eccentric with reference to the rotor axis and which is located only in part within the confines of the rotor. The guide Walls 7, 8 are connected to or integral with the inlet portion 9 and actually merge into the diffuser 10 whose walls are perforated or apertured in a region adjacent to the gap G, i.e., the perforations are formed in the end portion 10a. The end portion 10a of the diffuser 10 is surrounded by an annular compartment 11 which is connected with the flue 3 by a pipe 12. The

parts 11 and 12 together constitute the aforementioned regulating unit. Alternatively, the compartment 11 may be directly or indirectly connected with the interior of the housing 1.

If the flue 3 does not draw combustion air from the chamber 1b, such air is supplied exclusively by the blower 3. The kinematic pressure produced by the blower is transformed -by the diifuser 5 into static pressure which is used to overcome the resistance offered by the partition 1a. The cross-sectional area of the right-hand end portion a of the diffuser 10 is greater than the crosssectional area of the left-hand end portion 13 of the diffuser 5. However, when the ue 3 produces little or no suction, the major part of the air stream issuing from the end portion 10a enters the end portion 13 as indicated by the arrows 14. If the suction in the ue 3 increases, suction in the compartment 11 also increases via pipe 12 so that a greater percentage of the boundary layer is withdrawn through the perforations or apertures of the diffuser 1t) and such air enters the compartment 11. Also, the thus withdrawn boundary layer causes an expansion of the air stream issuing from the end portion 10a so that a higher percentage of such air flows in the direction indicated by arrows 15, i.e., through the gap G, and bypasses or misses the end portion 13.

The operation of the improved apparatus will be more readily understood with reference to the diagram of FIG. 2. The throughput V (produced by -suction prevailing in the ue 3 and/ or by pressure generated by the blower B) is measured along the abscissa 30. The pressure P of the blower B is plotted at the positive side of the ordinate 31. The suction K prevailing in the flue 3 is plotted at the negative side of the ordinate 31. The upper branch 21 of the curve shown in FIG. 2 represents the throttling curve of the blower and the lower lbranch 22 indicates the dependency of the throughput from the suction K. If such suction K rises to the value 23, the throughput V increases by a value 24. In order to keep the throughput constant, for example, to maintain the throughput at a value 25, the throughput produced by the blower B must be re- -duced by a value 26 which corresponds to the value 24. This is achieved by deliecting some of the air stream through the gap G as indicated by the arrows shown in FIG. l, and such deection is proportional to the rise in suction K. By properly selecting the configuration of the diffuser 10 and the size and distribution of its perforations, the curve 27 (which represents the amount of air that has bypassed the diffuser 5) can be selected in such a way that it is a mirror image of the branch 22 so that the resultant curve 28 is parallel with the ordinate 31 indicating that the flow of combustion air into the burner housing 1 remains constant, i.e., that such iiow is independent of the draft.

My improved apparataus may be put to use whenever and wherever the ow of a fluid at a constant rate is opposed by one or more obstructions whose resistance to flow varies within a wider or narrower range. In many instances, particularly in burners for gaseous or liquid fuel, it is actually desirable to oppose unimpeded flow of a Huid, e.g., combustion air. For example, in a burner, the stoi-chiometric ratio of fuel to combustion air should be selected in such a way that the combustion of fuel is complete and produces a minimum of residue. If the draft in a flue changes in response to changes in atmospheric pressure, the rate at which combustion air is fed to the burner must be altered accordingly. Conventional burners are normally combined with forced circulatiton blowers;

for example, a burner which is installed in or on a vehicle will receive combustion air which is deflected from head wind. The rate at which combustion air is supplied to the burner must be regulated, for example, by controlling the rotational speed of the rotor in a blower which necessitates the provision of complicated control systems. Alternatively, the flow of combustion air must be throttled which results in considerable losses in energy.

The improved apparatus fully avoids such drawbacks 'of conventional structures by conveying a stream of air or another fluid along a path a portion of which (between the diifusers 10 and 5) is unconiined and by comprising a regulating unit (including the compartment 11 and pipe 12) for deflecting in the unconfined portion of the path such quantities of conveyed uid that the rate of deection reects changes in resistance to the ow of uid along the path. Thus, and referring again to FIG. 1, the deection of the air stream in the gap G between the diffusers 10, 5 will increase proportionally with increasing suction in the flue 3, pipe 12 and compartment 11. Thus, the blower B need not be adjusted at all and it is equally unnecessary to throttle the flow of Huid from the blower. The fluid which escapes in the direction of arrows 15 can be released into the atmosphere or is conveyed to another locale of use, for example, to the suction side of the blower B.

An important advantage of the blower B is that its negative reaction is very low. The term negative reaction is intended here to indicate that the type of blower in question produces substantially only acceleration of the air, but no increase in air pressure. In other words, the energy of the accelerated air is transformed into pressure only in the diifuser arranged downstream, contrary to radial and axial type blowers. Only such types of blowers can concentrate all of the energy in a single stream of fluid, i.e., the entire energy is supplied in the form of kinetic energy. This kinetic energy is converted into static pressure on entry of the stream into the diffuser 5.

When the improved apparatus is installed in a vehicle, for example, to supply combustion air to a small burner, the blower B can be replaced by an intercepting nozzle whose intake end faces the head wind. In such apparatus, the nozzle (i.e., the pressure generating device) also constitutes an obstruction offering a variable resistance to the inow of air. The deflection of a portion of the unconned air stream can take place under the action of head wind or by providing an annular compartment which surrounds the nozzle. The compartment has inlet openings which face the head wind and outlet openings which face away from the head wind. As the speed of the vehicle increases, the quantity of air which enters the com-partment increases and such air escapes through preferably nozzle shaped outlets of the compartment. The jets which issue from such outlets tend to attract the stream of air which issues from the intercepting nozzle whereby the stream of air is partially deflected and the extent of such deiiection is proportional to the speed of the vehicle. The remainder of the stream flows at a constant rate and is mixed with fuel in the burner.

The blower B of FIG. 1 may be combined with a valve, such as a flap which extends in parallelism with the axis of the rotor and may be adjusted about a pivot parallel to the rotor axis. The length of this flap preferably equals or approximates the axial length of the rotor.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features which fairly constitute essential characteristics of the generic and specic aspects of my contribution to the art and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is:

1. A fluid conveying apparatus, comprising a conduit having an inlet portion, an outlet portion and an intermediate section located between said inlet and outlet portions said conduit further comprising a first diffuser providedwith said inlet portion and a second diffuser provided with said outlet portion, said diffusers having adjacent ybut spaced portions together constituting said intermediate section and dening between themselves a gap wherein the iluid stream owing from said rst diiuser toward said second diluser remains unconiined; an obstruction connected with one of said portions and arranged to offer a constant resistance to the ow of iluid therethrough; fluid supplying means for ldirecting a Stream of Huid into said inlet portion; means for varying the pressure of said fluid at the downstream side of said obstruction; and regulating means responsive to changes in Said pres-sure for withdrawing from said intermediate section such quantities of Huid that the rate of iluid ilow through said outlet portion remains constant, said obstruction being connected with said outlet portion and wherein said means for varying the fluid pressure comprises a pipe arranged to draw a variable amount of fluid from said first diiuser whereby such iiuid enters via said gap, said regulating means comprising a compartment outwardly adjacent to said first diffuser and communicating with said pipe, and apertures provided in said iirst diiuser to constitute passages for the How of uid from the interior of said first diiuser into said compartment whereby the quantity of uid flowing from said rst diffuser into said compartment is a function of the pressure prevailing in said pipe and the combined amount of fluid entering said second diffuser from said first diffuser and via said gap remains constant.

2. An apparatus as set forth in claim l, wherein said means for varying the pressure comprises a lirst pipe which offers a variable resistance to the flow of tluid therethrough and said fluid supplying means is a blower connected with said inlet portion and arranged to supply a fluid stream at constant pressure, said regulating means comprising a second pipe connecting `said rst pipe with said intermediate section.

3. An apparatus as set forth in claim 1, wherein said compartment is an annulus surrounding said rst diffuser adjacent to said gap and said regulating means further -comprises a second pipe connecting said rst named pipe with said compartment.

4. An apparatus as set forth in claim 1, wherein said obstruction constitutes part of a burner and said pipe constitutes a flue for discharging products of combustion into the atmosphere whereby the draft in said ilue varies independency on atmospheric conditions.

References Cited UNITED STATES PATENTS 1,896,910 2/1933 Merkt 158-1 2,155,279 4/1939 McMahan 110-72 2,414,322 1/1947 Mock 261-36 FREDERICK KETTERER, Primary Examiner. 

1. A FLUID CONVEYING APPARATUS, COMPRISING A CONDUIT HAVING AN INLET PORTION, AND OUTLET PORTION AND AN INTERMEDIATE SECTION LOCATED BETWEEN SAID INLET AND OUTLET PORTIONS SAID CONDUIT FURTHER COMPRISING A FIRST DIFFUSER PORVIDED WITH SAID INLET PORTION AND A SECOND DIFFUSER PROVIDED WITH SAID OUTLET PORTION, SAID DIFFUSERS HAVING ADJACENT BUT SPACED PORTIONS TOGETHER CONSTITUTING SAID INTERMEDIATE SECTION AND DEFINING BETWEEN THEMSELVES A GAP WHEREIN THE FLUID STREAM FLOWING FROM SAID FIRST DIFFUSER TOWARD SAID SECOND DIFFUSER REMAINS UNCONFINED; AN OBSTRUCTION CONNECTED WITH ONE OF SAID PORTIONS AND ARRANGED TO OFFER A CONSTANT RESISTANCE TO THE FLOW OF FLUID THERETHROUGH; FLUID SUPPLYING MEANS FOR DIRECTING A STREAM OF FLUID INTO SAID INLET PORTION; MEANS FOR VARYING THE PRESSURE OF SAID FLUID AT THE DOWNSTREAM SIDE OF SAID OBSTRUCTION; AND REGULATING MEANS RESPONSIVE TO CHANGES IN SAID PRESSURE FOR WITHDRAWING FROM SAID INTERMEDIATE SECTION SUCH QUANTITIES OF FLUID THAT THE RATE OF FLUID FLOW THROUGH SAID OUTLET PORTION REMAINS CONSTANT, SAID OBSTRUCTION BEING CONNECTED WITH SAID OUTLET PORTION AND WHEREIN SAID MEANS FOR VARYING THE FLUID PRESSURE COMPRISES A PIPE ARRANGED TO DRAW A VARIABLE AMOUNT OF FLUID FROM SAID FIRST DIFFUSES WHEREBY SUCH FLUID ENTERS VIA SAID GAP, SAID REGULATING MEANS COMPRISING A COMPARTMENT OUTWARDLY ADJCENT TO SAID FIRST DIFFUSER AND COMMUNICATING WITH SAID PIPE, AND APERTURES PROVIDED IN SAID DIFFUSER TO CONSTITUTE PASSAGES FOR THE FLOW OF FLUID FROM THE INTERIOR OF SAID FIRST DIFFUSER INTO SAID COMPARTMENT WHEREBY THE QUANTITY OF FLUID FLOWING FROM SAID FIRST DIFFUSER INTO SAID COMPARTMENT IS A FUNCTION OF THE PRESSURE PREVAILING IN SAID PIPE AND THE COMBINED AMOUNT OF FLUID ENTERING SAID SECOND DIFFUSER FROM SAID FIRST AND VIA SAID GAP REMAINS CONSTANT. 